Armor-piercing projectile



4.1918. 1,381,638. PatentedJune M, 1921-.

[aventura ,7170-6 emn 'HADFIELD Bart. F. R. S.,

uhu-TED STATES vPATENT OFFICE;-

ROBERT ABBOTT HADFIELD, or' WEsTMINsTER, ALEXANDER GEORGE McxENzIE JACK,OE SHEFEIELD, AND ISAAC BERNARD MILNE, OF TOTLEY, ENGLAND.

ARMOR-PIERCING PROJEGTILE.

Specification of Letters Patent. Patented June 14, 1921.

f Application led October 4, 1918. Serial No. 256,890.

To all whom z't may concern: J

Be it known that we, Sir ROBERT ABBOTT ALEXANDER GEORGE MCKENZIE JACK,and ISAAC BERNARD MILNE, subjects of the King of Great Britain andIreland, residing, respectively, at

Westminster, England, Sheffield, in the county of York, En land, andTotley, in the county of Derby,ngland, have inyented Improvements in orRelating to Armor- Piercing Projectiles; of which the following isaspecification. s'

This invention relates to the manufacture of armor piercingprojectilesor shells of all calibers, particularly of large diameter, sa'y oftwelve inches and upward, designed to perforate thick hard faced armorplates without becoming broken upJ or broken to such an extent as tointerfere with their subse uent desired action.

or thispurpose in the specification of another application for LettersPatent filed 28th Jne 1915,.v Serial No. 36886 there are describedprocesses for the production of such a projectile madeoffnickel-chromiumsteel, according to which the projectile, after being formed to shape,as by casting it solidI and then, after suitably annealing it, pressingit toshape in a suitable press,\is hardened by heating it all over in asuitable furnace .f to a hardening temperature, and then dipping itdirectly point downward .to its base end inA a cooling medium properlyto cool and harden it. The projectilethushardened all over isthentempered byfheating its base portion to a suitable tempermgtemperature in a tempering furnace While its pointedend portion isimmersed, pointdownward, to a Suitable depth in water, after which it iscooled in a suitable cooling medium.'-

According to one example describedin thesaid former specification,carried out'with a twelve inch projectile having a length of aboutthirty four inches and made of nickelchromium steel having the followingap- Y proximate composition, namely, carbon .6 to

.7 nickel 2 to 3%, and chromium 2 to 3%, for example, carbon about .66%,nickel about 2.52% and chromiumcabout 2.31%, the projectile was heatedallUover to a hardening temperature while its point was protected fromdirect contact with the heat, so that the external shouldfr portion ofthe shell had a temperature o .to a dept `1n water kept cold. .It wasthen allowed to about 915 C., to 920 C., the inner surface of coreadjacent to the shoulder portlon being found to have, in

,the example given, a temperature of about oil, as the cooling medium,to its base end and holding it there until properly hardened, thecooling being effected from the exter1oralone, vthat is to say withoutadmitting anytcooling medium to the interior of the shell. VThe hardenedprojectile was f afterward subjected to a second or tempering treatmentconsisting in heating its base or body portion in a furnace to atemperature of about 67 0to 705 C., its-interior or core having atemperature of about 605 C. while its lpointed endportion was immersedof about eight andy a half inches cool down in the furnace to abase orbody temperature of about 320 C. to 300 C.,

and an internal yor core temperature of about.

290 to 255 C. whereupon it was quenched outright in water. When thustreated, the pointed portion of the shell for about the irst ten inchesof its length has al'ball hardness of 600 and over, the weightpf thispor-1 tion comprising about 12% of tlie total weight of the projectile,the ball hardness varying from* 600 at ten inches from the point to 418at fourteen inches, 311 at eighteen inches and 24:1 at the base end ofthe shell. A

According to a second example, carried 4outwith a fourteen'inchprojectile'having a length of about fifty two inches and madeofnickel-chromium steel having the following approximate composition,viz, carbon .69, nickel 2.53% and chromium 2.70%, the projegtile washeated all over, while its point was protected from direct contact withthe heat, so that the'external shoulder portion of the shell had atemperature of about 930 C., the inner surface or core adjacent to theshoulder being found to have in this example a temperature of about 900to 905 C., the point a temperature of'about 875 C., and the base atemperature of about' '850 C. 'llhe projectile thus heated was thendipped in oil to its`base end and held in that positioriuntilpractically cold, the cooling .being effected Wholly from the exteriorinward. The hardened projectile was after-V as A'b'a Lrdness, the I yness corresponding to 500 to 600 is hereinafter referred to ascorresponding to 400. to 500 as C ball hardness, Vthat corresponding to300 to 400 as D ball hardness and that below 300 as E ball hardness.

Now the presen ject, better toy adapt armor piercing projectilesproduced according to the invention described in the' formerspecification to suc cessfully withstand, when suitably capped, thestresses to which they are subjected when striking a hard faced armorplate, particularly under certain special conditions,

namely,- at comparatively low velocitiesV and at considerable angles andsuch as obtain for instance in long range iring.

For the purpose mentioned, an armor piercing projectile, formed ofnickel-chromium steel of suitable composition, is heated, liardenefLandtempered i that the zones of steel of the projectile are moved to thoseof the tioned in the said former specification, -so that there is a muchless volume or percent-A age of steel of A ball hardness than waspreviously the case and so that steel of E ball hardness extendsapproximately from a pointcorresponding to or slightly rearward forwardrelatively DL bfabutl S7 Ci;fat;afpo i responding to the junction of t ehead B ball hardness, that t invention hasfor its ob in such a manner jv A, B, C, D and AE ball hardness in the ogival shaped head of articularprojectiles menwith the body of the projectile, while the head portionis [immersed point downward toi a comparatively small depth in water toobtain the desired result, after which therprojectile is cooledl down-uin the tempering plant to an internal or corejtemperature to 120 C. andthen withdrawn from the tempering furnace and cooled, it may be bquenching it outrigh .in a cooling liqui for example water, or bydipping it point of the order of say about 320 Ct f downward in acooling liquid, for example' water, `to a suitable zone depth, or it maybe allowedito c oolfsloyvly in air, br it may be cooled down toatmospheric temperature before removal from vthev tempering plant. Theduration of the tempering treatment, .the dep th to which the headportion of the projectile is`i'mmersed in' water during such treatment(anl the mode of finally cooling the tempered projectile can be variedand depends to some extent upon the size kof the projectile andv alsoupon the percentage of steel in the zones of steel having A', B, C, Dand E ball hardness desired. Inall cases, the tempering treatment issuch that the percentage of the zone' of steel of Av ball hardness inthe head of the projectile shall be small.' The zone of A ball hardness'is disposed at the forward end or nose of the projectile and togetherwith the succeeding zones B, C and D are in the form of shallow orflattened cups arranged one behind the other and extending more or lesstransversely, as indicated approximately by the dotted lines z and a inthe drawing the -rearward zone of E ball hardness extending throughoutthe body of the projectile to the base end thereof; Zones of hardness ofthe type mentioned are hereinafter referred to for brevity as transversehardnessf Such type of hardness is obtained by immersing the head of thehardened projectile in water to a de th up to say about 2 to 5 inchesfor say a ourteen inch` projectile. The proportions and positions ofthehdifferent zones of A, B, C, D and E ball hardness can be varied asmay be required and according to the type ofattack desired, by varyingthe depth of immersion of the head of the hardened projectiles during'the tempering treatment.

Satisfactory results have been obtained with a percentage of A ballhardness ofthe order of about .25 to 2% of the total weight of theprojectile, of B ball 4hardness of the.

order of about 2 to 6% of C ball hardness of the order of about 5 to 10%of D ball hardness of the order of about 14 to 20%, the remainder of theprojectile vbeing of E ball hardness and extending from around about andover the forward end of the core or chamber of the projectile to thebase of the projectile. To enable the tempering of hardened projectilesto be successefully carried out in a readily controllable manner and soas to enable a number of projectiles having uniform characteristics tobe obtained, the tempering of theN projectile may advantageously beeffected in the manner and by the means described in the specificationof another application for lLetters Patent filed 27th June, 1914, SerialNo. 847680.

According to one example, a hardened'and tempered projectile having adiameter of 13.5 inches and which gave satisfactory re-4 sults undertest, was made of nickel-chromium 'steel containing about .65% ofcarbon, 2.64% of nickel and 2.6% of chromium and hardened at atemperature of about 820 to 830 C. by dipping it point downward to itsbase end into water where it was allowed to remain until properlyhardened and then removed.

The projectile thus hardened all over was then subjected to thetempering process. For this purpose the body and base portin of theprojectile was heated in a suit- A. able tempering furnace, su'ch asthat hereinbefore referred to, externally to a,tempera.

ture of the order of about 760i C. at the base and internally to atemperature of the order of about 660 C. at the forward end of the'core,While the-head portion of the pro, jectile was immersed point downwardto a pering plant to an internal' or core 'temperature o f about 120 C.and then the projectile was removed from the tempering furnace.

The toughened walll or body of the projectile at Va point 17 from thebase had an elastic limit of 41 tons to the square inch and a tensilestrength of 50 tons with 17% elongation and 33% reduction in area 'atthe break. At the base the elastic limit of the steel was 35 tons, theultimate strength 49 tons, the, elongation 21% and reduction in area36%. The steel at the forward end of the core had a ball hardness ofabout 250. The zonesAl, B, C, and? D ball hardness were of the typeherein referred to as transverse hardness.

In another example, a 15 inch projectile of nickel chromium steelcontainlng .64% carbon,2.72% Ni. and 2.75% Cr., was heated externally toabout 840 C. at the shoulder and point, 835 C. at the base and to aninternal or core temperature of 820 to 825 C.; it was then dipped inwater to base until properly hardened.. L It was afterward-inbeforedescribed It was afterward cooled while in the temperingfurnace to a core temperature of about 120 C. and-then removed andquenched. The toughened wall or body of the projectile at a point 19inches from the base had an elastic limit of 46 tons, a tensile strengthof 54 tons, with a i15% elongation and a reduction in`area of 31% at thebreak. At the'base the steel had an elastic limit of 41 tons and atensile strengthef 53 tons with 19% elongation and 33% reduction in areaat the break. The

steel at the forward end of the core had aa ball hardness of about 290.Inthis example the A@ B, C, and D zones of ball hardness were also `ofthe type Vreferred to' as transverse hardness.

To adaptan armor piercing shell hardenetdand tempered as described foruse, it is provided with a suitable cap, preferably made ofa`nickel-chromiu1n steel with a hardened front portion. c Y. j l

What we claim is 1. The process of hardening an` armor piercingprojectile made of nickel chromium steel which consistsfin heating theprojectile all over to a hardening temperatureof the order of about 800to 860J C., then dipping it point downward to -base `in water andfal--hardened and then removing it lowing it to remain 'there until properlywhead portion of the projectile is immersed p from the water.

2. The process of treatingan armor piercing, projectile made of nickelchromium steel -which consists in heating the projectile all. over top ahardening temperature of the order of about800 to 860 C. then dippingi'tpoint downwardv to base 1n water and allowing it to remain there untilproperly hardened, then removing. it from the water and subsequentlysubjectingf the hardened projectile to a suitable tempering .treatmentwhile maintaining its point cool.

3Q The process of hardening and tempering an armor piercing projectilemade of nickel chromium steel which consists in heatingthe projectileall over to a hardening tempera- .ture of the order of about 800 to 860C.,

` ward cooling the pro'ectile.

then dipping it point downward to base in water and allowing it toremain there until properly hardened, then heating the hardenedprojectile to a tempering temperature of the order of about 7 60 C.while the point of the projectile is immersed to a relativelyv smalldepth in a cooling liquid and after 4. The herein descri ed processofharden-A ing an armor piercing proj ectile which .con-v sists in tproducing a projectile of the approximate composition of carbon about.58 to l.69%, nickel about 2 to 3.5%l and chro-v mium about 2 to 3%,heating the pro'ectile all over Yanddipping it while at a har eningtemperature of the order of about 800 to 860 C., point downward to baseim water and allowing it to remain there untilproperly hardened and thenremoving it.

5. The process of hardening and tempering an armor piercing projectilemade of nickel chromium steel which consists in dipping the projectilewhile at a hardening temperature of the order of about 800 to 860 C. inwater so as to harden it all over, allowingit to remain therein uyntilproperly hardened, re-Y moving the projectile from the water, afterwardheating the projectile rto a suitable tempering temperature while itspointed en portionis immersed to a relatively smal 'peo depth in acooling liquid, and finally cooling the projectile.

f 6. The process of hardening and tempering @n armor piercing projectilemade of nickel chromium steel which consists in dipping the projectile,while at a hadening temperature4 of the order of about -800 to 860 C.,point downward to base in water, allowing it to remain there untilproperly hardened, .removing the water, afterward heating t e projectileAto an external .temperature of the order or about 760 C. .and a coretemperature of the order `of about '570 to 700 C. at therpart'correspondin to the junction of the head l at 4the point 'and thencooling the projectile.

pro'ectile from the of the projectile while the.

moving the projectile from the water, afterward heating the projectile,to an-external temperature of the order of 'about 760 C. and a coretemperature ofthe order of about 570 to 700 C. at the part correspondingto the junction of the head with the body of the -lprojectile while thehead portion of the projectiley is immersed comparatively small depth inwater, afterward cooling the projectile down to an inter. nal or coretemperature of the order of about 320 to 120f C. inthe temperingfurnace, then removing the lprojectile from the tempering i furnace andthereto.

8. The process of producing a hardened and tempered nickel chromiumsteel armor piercing projectile having its head of A, B, C, D and E ballhardness as herein dened/ y the zone of A ball hardness being disposed.at the point of the projectile and the zpne of E ball hardness extendingapproximately from a point corresponding to or slightly rearward ofthejunction of the ogive and parallel portions 'of the ,projectile to thebase end of the projectile, which consists in heating the projectile allover and dipping it while at a hardening temperature of the order ofaboutv 800 to 860 C., point down- 105 ward to base in water, allowing 1tto remain there until properly'hardened, then removing the projectilefrom the water and heating it in a tempering furnace to a temperatureexternally of the order of about 7609110 C.' and internally to atemperature of the order of about 570 to 700 C. at the junction of thehead with the body of the projectile while the pointed end portionoffthe projectile is immersedin water to a depth of l from about two tofive inches in the case of a fourteen inch projectile, yso that thepercentage of the zone of steel of- A ball hardness of the projectileshall be small, n

y9. The process of producing a hardened and tempered nickel chromiumsteel armor iercing projectile having its head of A, B, D andE ballhardness as herein detnel` point downward to a vthe zoneof `A ballhardness being disposed 1,25

base in water, allowing it 75 to remain there until properly hardened,re-

nally cooling it externally 90 end of the projectile, which consists inheating thc projectile all over and dipping it While at a hardeningtemperature ofthe order of about 80() to 860 C., point downward to basein water, allowing it to remain there until properly hardened, thenremoving the projectile from the Water and heating it in a temperingfurnace to a temperature externally of the order of about 760o C.- andinternally to a temperature of the order oi about 570 to 700C C. at thejunction of the head with the body of the projectile While the pointedend portion of the projectile is immersed in water to a depth of fromabout two to five inches in the case of a fourteen inch projectile sothat the percentage of the zone of steel of A ball hardness at the pointof the projectile shall be small, and then cooling the projectile partlyin the tempering furnace and partly externally to such furnace.

Signed at London, England, this nineteenth day of August. 1918.

ROBERT ABBOTT HADFIELD. ALEXANDER GEORGE McKENZlE JACK. ISAAC BERNARDMILNE.

